1. Field of the Invention
The invention generally relates to devices for minimizing work-related injuries caused by the use of computers, and more particularly relates to ergonomic computer-pointing devices such as an ergonomic computer mouse.
2. Description of Related Art
It is well known that the extended use of a computer-pointing device, such as a computer mouse, can cause a computer user to suffer from cumulative trauma disorder (CTD) or repetitive strain injuries (RSI). Computer users are often afflicted with pains in the hands and the wrists caused by excessive wrist movements such as flexion and hyperextension of the wrist. Computer users can also suffer from soreness and fatigue in the shoulders and the neck due to excessive arm and shoulder motions associated with use of computer-pointing devices.
Long period of repetitive motion associated with the use of the computer mouse coupled with incorrect hand posture while using the mouse may cause disorders in the hand, wrist, elbow, shoulder, and neck, such as carpal tunnel syndrome. Carpal tunnel syndrome is the numbness, tingling and loss of strength of the hand and wrist, and is caused by stress on the wrist induced by repetitive wrist and finger motions. Repetitive stress injuries, such as carpal tunnel syndrome, can be disabling and are costly, in terms of both medical expenses and lost work time.
The prior art includes several support devices that were used in conjunction with the computer pointing device, such as a computer mouse, to reduce the stress and risk of injury associated with the frequent and repetitive motion necessary in the use of the computer mouse. As described more completely below, typical support devices include stationary or movable apparatus supporting the hand, the wrist or the palm.
U.S. Pat. No. 5,451,020 to Smith et al. and U.S. Pat. No. 5,228,655 to Garcia et al. disclose examples of stationary wrist support devices, also called wrist rests. Wrist rests are typically pads placed in front of the keyboard or the mouse. The height of the pad is selected to support the wrist to elevate the hand to be level with the forearm. Wrist rests alleviate the stress on the wrist by avoiding prolonged bending up and down of the wrist. However, studies have shown that pressure on the underside of the wrist can irritate wrist tissue and increase the risk of carpal tunnel syndrome. Furthermore, wrist rests do not protect the wrist from excessive side-to-side bending, which can cause injuries to the tendons in the wrist. Thus, stationary wrist rests are not a satisfactory means to protect computer users from repetitive stress injuries.
Other types of stationary support devices include a palm rest disclosed in U.S. Pat. No. 5,433,407 to Rice, and a computer mouse support having an upwardly inclined orientation disclosed in U.S. Pat. No. 5,203,845 to Moore.
Prior art support devices also include movable apparatus. U.S. Pat. No. 5,490,647 to Rice discloses an example of a movable hand support also called a palm rest. Movable palm rests such as that disclosed by the Rice ""647 patent tend to fall over easily during use and at best support the palm indirectly.
U.S. Pat. No. 5,340,067 to Martin et al. discloses a movable hand and wrist support 110 for computer mouse 112 as shown in FIG. 1. Support 110 holds mouse 112 within a retainer 114. The user rests hand 113 on support 110 such that hand 113 is on the same plane as mouse 112.
Movable hand and wrist support 110 disclosed by Martin et al. has several disadvantages. First, support 110 has a raised area 116 near the center of support 110 intended to apply gentle pressure on the palm of hand 113. As mentioned previously in reference to palm rests, applying pressure to the center of the palm can cause carpal tunnel syndrome and is highly undesirable. Second, fine mouse movements are made more difficult because the user must move mouse 112 and support together 110. Third, support 110 does not maintain hand 113 in a neutral position because the user has to twist his/her wrist to place hand 113 on the flat surface of support 110.
In addition to the disadvantages described above, prior art support devices are not satisfactory because such devices tend to force the user to focus movement of the user""s hand and shoulder in one field of motion only. Stationary palm rests restrict arm and shoulder movement, and force the user to move the wrist only in manipulating the mouse. The movable wrist/hand support disclosed by Martin et al. completely eliminates wrist motion, thereby forcing the user to move the arm and shoulder exclusively in manipulating the mouse. Extended and repetitive motions focused on either the wrist or the shoulder can cause cumulative trauma disorders.
Another problem with wrist pads is that a movable wrist pad is not easily manipulated by the user. Consequently, as the mouse is moved about, either the mouse or the movable wrist pad must be repositioned to maintain the movable wrist pad in the proper relationship to and separation from the computer mouse.
One solution to this problem has been to attach the computer mouse to the movable wrist pad using a spring loaded tether. The tether is contained in the wrist pad and is attached to the head of the computer mouse using a VELCRO fastener. VELCRO is a registered U.S. trademark of Velcro U.S.A. Inc. and is a synthetic material having complementary parts, which adhere to each other when pressed together.
This configuration has several shortcomings. First, the configuration is still a computer mouse and a wrist pad and so the configuration suffers from the same basic shortcomings as the wrist pads described above. Second, the combination does not assist the user in using different muscle groups.
In particular, if the wrist pad and the computer mouse are moved to keep the two together, only the arm and shoulder muscles are used. To avoid this the user must pull the mouse away from the wrist pad, and maintain enough pressure on both the mouse and the wrist pad to maintain the separation. This adds additional unnatural stresses on the user""s hand, fingers and wrist, and causes the user to attempt to manipulate the mouse using the fingers while maintaining pressure on the wrist pad with the wrist so that is does not move. If the user lifts the wrist, the spring-loaded tether moves the wrist pad against the mouse. This combination also reduces user efficiency because each time the user reaches for the mouse, the user must apply pressure on the wrist pad, and then move the mouse a sufficient distance from the wrist pad so that the mouse can be used. All of these motions are unproductive and only add to the stresses associated with using the combination device.
Also, the VELCRO fastener is not a fixed connection and if the user simply continues to move the mouse when the tether is fully extended, the VELCRO fastener may pull loose. Finally, the combination is bulky and requires sufficient desk area to facilitate moving both the wrist pad and the computer mouse. In fact, the combination is difficult to move to another location on the desktop, and difficult to move for cleaning the desktop. Users have also indicated that the combination makes it more difficult to clean the mouse ball.
Another combination simply used a VELCRO fastener to affix a palm rest to the computer mouse. The palm rest was supported by a small square bottom that did not move easily and the palm rest put pressure on the center of the hand, which as described above is undesirable. This combination suffers from the same shortcomings as an ergonomic mouse in that the combination does nothing to encourage the user to use vary the muscle groups used in manipulating the computer mouse. In fact, the combination can only be moved about using the arm and shoulder muscles, which can result in elbow and other injuries. Also, this combination makes fine control of the cursor, which is normally done using the fingers, extremely difficult.
To eliminate the problems with the various support devices, many manufacturers are changing the shape of the single unit computer mouse and some are including a larger area for hand and palm support. The intention is to cause the user to align the hand and wrist in the neutral position while grasping the mouse. While aligning the hand and wrist in a neutral position is desirable, the alignment alone is not sufficient to assure that injuries caused by repetitive use of only certain muscle groups are eliminated.
Accordingly, there is a need for a computer-pointing device, such as a computer mouse, which can reduce stress and help to prevent injuries while not impeding the productivity of the computer user.
According to the principles of this invention, an ergonomic dual-section computer-pointing device, that includes a cursor control section fixedly and movably connected to an ergonomic hand support section, reduces stress and helps to prevent cumulative trauma disorder. The ergonomic dual-section computer-pointing device does not compromise the productivity of a computer user. For example, the ergonomic dual-section computer-pointing device facilitates the user moving his/her hand from a computer keyboard to a proper position with respect to the computer-pointing device without looking at the computer-pointing device, or having to reposition any part of the device to obtain a proper relationship between the sections of the device. Therefore, delays associated with interpreting work and visually seeking the location of the computer-pointing device, or in repositioning a part of the device so that the device can be used are greatly reduced or eliminated.
The ergonomic dual-section computer-pointing device of the invention keeps the hand in a neutral position which imitates the natural roll of the hand, the wrist and the forearm, and therefore minimizes stress and fatigue while using the computer-pointing device. In addition, the ergonomic dual-section computer-pointing device positions the hand in the same plane and as close as possible to the cursor control section which in turn allows the user to easily manipulate the computer-pointing device of this invention.
The ergonomic dual-section computer-pointing device is not only compact and inexpensive, but also is adaptable to an existing desktop and does not take up too much desktop space. Hence, the ergonomic dual-section computer-pointing device of this invention overcomes the shortcomings of the prior art hand support devices, and ergonomic computer-pointing devices described above.
A significant ergonomic feature of the ergonomic dual-section computer-pointing device is that the device facilitates two fields of motion. In a first field of motion, the fingers, the hand, and the wrist are used to move the computer-pointing device of this invention, and in a second field of motion, the arm and shoulder are used to move the computer-pointing device. The two fields of motion inhibit excessive use of a particular muscle group, which in turn reduces the likelihood of injury associated with repetitive stresses and motions of that particular muscle group.
Specifically, in the first field of motion, the fingers, the hand, and the wrist are used to manipulate the cursor control section while the ergonomic hand support section remains substantially stationary. In a second field of motion, the arm and shoulder are used to move the cursor control section and the ergonomic hand support section in unison. Hence, the two fields of motion inhibit excessive use of a particular muscle group, which in turn reduces the likelihood of injury.
When a user extends a hand to the ergonomic dual-section computer-pointing device, the ergonomic hand support section guides the hand into the proper position for using the cursor control section, and guides the hand into a neutral position so that the hand, wrist, and forearm are in the same natural alignment as when the palm of the hand rests naturally on a flat surface.
As indicated above, the cursor control section of this invention is fixedly and movably connected to the ergonomic hand support section. Specifically, a coupler fixedly and movably attaches the cursor control section to the ergonomic hand support section. The fixed attachment permits the cursor control section to move over the first field of motion. Specifically, the coupler allows the user to move the cursor control section until the cursor control section contacts a control point of the ergonomic dual-section computer pointing device. In one embodiment, the control points are internal to the device, which means that the control points are defined by the coupling mechanism. In another embodiment, the control points are a combination of internal control points and external control points. In this embodiment, the internal control points are defined by the coupling mechanism, and the external control points are defined by a surface of the ergonomic hand support section and a surface of the cursor control section.
In either an internal embodiment, or a combination of an internal and external embodiment, when a control point is contacted, the user is alerted that the range of fine movement is reached and the user must employ the second field of motion to move the cursor control section further in that direction. In this manner, the ergonomic dual-section computer-pointing device inhibits excessive side-to-side bending of the user""s wrist and inhibits excessive use of only one group of muscles.
When the cursor controlled by movement of the cursor control section must be moved further than is permitted within the first field of motion, the user grasps the cursor control section, and effortlessly slides the combination of the ergonomic hand support section and cursor control section around the work surface using the arm and shoulder muscles while maintaining the hand, wrist and forearm in the neutral position.
The ergonomic hand support section includes a first surface e.g., a top surface that in turn includes a palm support region. A little-finger support region extends from the palm support region. A thumb support region also extends from the palm support region. The thumb support region and the little-finger support region are positioned with respect to the palm support region so that when a user""s palm rests on the palm support region, the user""s little finger curls in a neutral manner about the device, and the thumb can grasp the cursor control section, i.e., the little finger and thumb are in a natural ergonomic position for the palm resting on a flat surface.
Hence, the thumb support region and the little-finger support region are ergonomically positioned with respect to the palm support region. In one embodiment, to facilitate the ergonomic positioning of the hand, the palm support region has a slope in a direction from the little-finger support region to the thumb support region.
In addition to the ergonomic positioning, in the embodiment that utilizes a combination of external and internal control points, the thumb support region and the little-finger support region define an opening positioned between the thumb support and little-finger support regions. Hence, a position of the thumb support region and a position of the little-finger support region also are selected to provide a size of the opening to permit the cursor control section have a desired range of motion within the opening. The opening has a shape similar to a portion of the cursor control section positioned in the opening, but the opening is larger than a head portion of the cursor control section thereby permits a limited range of movement of the cursor control section within the opening.
The ergonomic hand support section has a second surface, opposite and removed from the first surface, and a perimeter surface connecting the first surface to the second surface. A portion of the perimeter surface, that bounds the opening and that is between the thumb support region and the little-finger support region, is a control surface.
As the user manipulates the cursor control section within the opening, the computer-pointing device may contact a point on the control surface. A point of contract between the computer-pointing device and the control surface defines an external control point for the first field of motion. Hence, the control surface, between the finger and thumb support regions, has one or more external control points that confine the range of movement of the cursor control section in the first field of motion.
In addition to the ergonomic features, the ergonomic dual-section computer-pointing device improves the efficiency of the user by eliminating the need to look at the device when placing a hand on the device. As the user""s hand moves over the ergonomic hand support device, one or more tactile indices provide tactile reference points for properly positioning the hand with respect to the computer-pointing device. In one embodiment, a combination of the first and second tactile indices is what permits the user to properly position the user""s hand on the device without looking at the device.
In general, the first and second tactile indices can be placed at any location on the first surface of the ergonomic hand support section that does not interfere with the natural positioning of the hand and wrist; that does not place unnatural pressures or stresses on the hand and wrist; and that guides the hand into the proper position with respect to the computer-pointing device. The two tactile indices on the first surface are separated from each other and orientated at an angle with respect to each other in one embodiment. The angle is selected to ergonomically position the hand with respect to the computer-pointing device.
In another embodiment, the two tactile indices are placed along opposite sides of the hand support device so that one extends from the thumb and palm support regions, and the other extends from the little finger and palm support regions. Further, a tactile index may extend only along a part of a side of the hand support device. Thus, the tactile indices may be diagonally separated across the surface of the hand support device. When the indices extend along the two sides of the hand support device, there may be a small angle between the two indices, but in this case, the indices are said to be substantially parallel.
In one embodiment, a first tactile index is a side index extending from the thumb support region and the palm support region. The second tactile index is a front index extending from a portion of the palm support region between the little-finger support region and the thumb support region. The side index is shaped to push a user""s hand toward the computer-pointing device. The front index is positioned so that no pressure is exerted on a center of a user""s palm resting on the ergonomic hand support device.
The first surface of the ergonomic hand support section also has a pressure relief edge surface extending from a portion of the palm support region opposite and removed from the opening to a portion of the perimeter surface. In one embodiment, the pressure relief edge surface is a convex surface.
In one embodiment, the second surface of the ergonomic hand support section has a plurality of rails affixed thereto. The plurality of rails permits smooth movement of the ergonomic dual-section computer-pointing device off and on any edge of the working surface. Each of the plurality of rails has a sliding surface and a beveled edge surface. The beveled edge surface surrounds the sliding surface and extends from the sliding surface to the second surface.
Thus, an ergonomic computer-pointing device of this invention has a cursor control section, an ergonomic hand support section, and a coupler interconnecting the cursor control section and the ergonomic hand support. The coupler movably and fixedly connects the cursor control section to the ergonomic hand support section to permit free movement of the cursor control section over a first field of motion while the ergonomic hand support section remains substantially stationery. However, the coupler limits a range of motion in a first direction in the first field of motion.
In one embodiment, the device of this invention also includes a pressure timing circuit coupled to the ergonomic hand support section. The pressure timing circuit measures an amount of time a user maintains pressure on the ergonomic hand support section and generates a time-out signal when the amount of time exceeds a predefined time.
The time-out signal is used to generate a warning to the user indicating that the user has maintained contact with the device of the invention for the predefined time. The warning can be generated by circuitry on-board the computer pointing device or alternatively, by a computer to which the computer pointing device is coupled. The pressure warning circuitry of this invention can be incorporated in any computer pointing device, or alternatively in any hand or wrist support.
In one embodiment, the coupler is a telescoping mechanism pivotally connected to the cursor control section and pivotally connected to the ergonomic hand support section. A set of crash stops is mounted in one or both of the ergonomic hand support section and the cursor control section about the telescoping mechanism to limit movement of the telescoping mechanism.
In another embodiment the coupler includes a cam opening oriented about a crash stop. A size of the cam opening and a size of the crash stop determine a range of motion in the first field of motion.